Objectives: 1) The pattern of liver failure in the surgical patient will be documented. Special emphasis will be placed on the role of bacterial sepsis. 2) The cellular immunologic responses of cirrhotics will be documented to see if depression accounts for the important role of sepsis in precipitating coma. 3) Extracorporeal hepatic assist devices will be designed, fabricated and tested in vitro and in vivo in the liverless comatose pig. Special emphasis will be placed on using liver cells suspended in an I.B.M. manufactured centrifuge which contains up to 500 grams of cells in contact with oxygenated perfusate or plasma. This unit, working in series with the I.B.M. cell-plasma separator, has the potential for providing a simple effective technique for extracorporeal liver assist in a unit that can be used repetitively over many weeks while a diseased liver can be given an opportunity to regenerate.